The present invention refers to a locking slider for a slide fastener and more particularly to a slide fastener, made entirely of plastics material and comprising a slider body with springable lock and a pull tab fastened at a bow at the slider body. The slider body is preferably an integral unit consisting of a lower and an upper slider plate being connected by a connecting separator. The present invention further relates to a method for producing such a slider.
A prior art locking slider is described in German Publication No. 1,811,663. The bow, which is integrally formed with the slider body, is open at one end for assembling the pull tab and the other end is provided with two incisions, producing a springable middle section acting as locking tooth which locks, through an opening in the body, with the interlocking members. The production of such a slider with an integrally formed body with lug and springable locking means necessitates a very complicated and expensive mould. Furthermore, due to the open-ended lug it is possible for the pull tab to be lifted off.
British Pat. No. 1,574,079 discloses a locking slider with a body made of two parts and a springable locking means forming a third part which has to be assembled, together with the pull tab. Furthermore, the pull tab is loosely enclosed in the lug so that for unlocking the slider the whole springable locking means has to be pulled up, ,causing a problem in terms of the strength of the lug.
British Pat. No. 1,377,451 discloses a locking slider having a body which can be produced integrally if an opening is provided in it for introducing a full-elliptic spring as locking means. Otherwise the body must be made in two parts. The mould for the body as well the spring are complicated and expensive parts.
French Publication No. 2,303,497 discloses a locking slider in which the body, lug and locking means are made integrally of plastics material. Theoretically, such a slider should be simpler than the above mentioned prior art. However, in practice the injection of such an integrally formed body with the lug and locking means is very problematic, leading to expensive and complicated moulds. The locking means, in the form of an arm, protrude from the body and the pull tab is freely mounted in the lug, causing problems with regard to the relative rigidity and springability of the arm.